Polymyositis

A 17-year-old man, who had received a diagnosis of juvenile polymyositis (PM) at the age of 1 year, developed recurrent spontaneous pneumothoraces and underwent surgical treatment by means of video-assisted thoracic surgery. Intraoperative observation and microscopic studies demonstrated numerous bleb-like lesions below the visceral pleura. To our knowledge, this is the first article that describes a case of spontaneous pneumothorax associated with PM. Our observation should lead to broadening of the spectrum of pleuropulmonary manifestations of PM.

(CHEST 2000; 118:1509-1511)

Key words: cyst-like lesions; juvenile polymyositis; spontaneous pneumothorax

Abbreviations: DM = dermatomyositis; PM = polymyositis

Polymyositis (PM) and dermatomyositis (DM) are related idiopathic inflammatory myopathies. Although spontaneous pneumothorax has been reported as a rare complication of DM,[1-4] to our knowledge, no case of PM associated with spontaneous pneumothorax has been reported. In this article, we describe a case of spontaneous pneumothorax in a 17-year-old patient with juvenile PM. Intraoperative and microscopic findings were unique, suggesting that pleural changes due to PM contributed to recurrent spontaneous pneumothoraces.

CASE REPORT

A 17-year-old man had received a diagnosis of juvenile PM when he was 1 year old, based on the following signs: his proximal muscle weakness (Gower's sign, +); elevated myogenic enzymes, including creatinine phosphokinase, 626 IU/L (normal level, 30 to 200 IU/L) and aldolase 10.3 IU/L (normal level, 1.7 to 5.7 IU/L); myogenic pattern of electromyogram; and histology. The myogenic enzymes were normalized during high-dose prednisolone therapy (2 mg/kg/d). He received prednisolone until age 9 years. From age 13 to 16 years, he was treated with growth hormone for his growth retardation.

In May 1997, right spontaneous pneumothorax was diagnosed for the first time. During the next 2 years, he was conservatively treated for recurrent pneumothoraces, four times on the loft side and three times on the right side. In June 1999, he had a right pneumothorax and was referred to our hospital for surgical intervention. There had been no previous attempts for prevention of recurrence, such as chest tube with sclerosis.

On admission, he was 155 cm in height and 27 kg in weight. In addition to systemic proximal muscular atrophy, he had prominent thoracic deformity and scoliosis. This skeletal abnormality was attributed to his muscular disease and to steroid therapy. Other musculoskeletal, collagen, and metabolic diseases that could cause skeletal abnormalities were ruled out based on his symptoms and clinical data. Chest radiograph showed right-sided pneumothorax. Chest CT, which had been performed before this pneumothorax occurrence, demonstrated bullae at the apex of both lungs (Fig 1, top) No evidence of pulmonary fibrosis was found (Fig 1, bottom). Pulmonary function testing showed severe restrictive impairment (vital capacity; 1.5 L; percent of predicted vital capacity, 38.2%; [FEV.sub.1], 1.37 L; percent: of [FEV.sub.1], 90.1%). Blood gas analysis while breathing room air demonstrated [CO.sub.2] retention (Pa[O.sub.2], 72 mm Hg; Pa[CO.sub.2], 60 mm Hg; pH, 7.34).

[Figure 1 ILLUSTRATION OMITTED]

On June 21, 1999, the patient underwent a right bullectomy under video-assisted thoracic surgery. Only one cystic lesion (about 5 x 10 mm) was identified at the apex of the right lung; however, almost all the surface of the visceral pleura was covered with numerous cystic lesions, about 0.5 to 1.0 mm in diameter. The larger cystic lesion was resected together with its surrounding tissue. Microscopic studies revealed nonspecific cystic lesion and multiple bleb-like lesions just below the visceral pleura (Fig 2). No evidence of interstitial fibrosis was found. The patient was extubated after 18 h of postoperative respiratory support and discharged 7 days after surgery.

[Figure 2 ILLUSTRATION OMITTED]

DISCUSSION

Juvenile PM/DM is an acquired inflammatory disease of unknown etiology that normally affects children [is less than] 15 years old. The disease is manifested as severe proximal muscle weakness and, in juvenile DM, cutaneous eruption is characteristic.[5] Muscle biopsies characteristically show patchy mononuclear infiltrates with perifascicular muscle fiber degeneration.[6] Juvenile PM/DM is considered as a part of the spectrum of PM/DM and is distinguished from the adult form in having a number of different clinical and pathologic features.[7] Development of calcinosis--subcutaneous and/or muscular calcification--is a more frequently encountered complication in juvenile PM/DM than in the adult form. Juvenile PM/DM is regarded as a syndrome rather than an entity because of its various clinical pictures.[6,8] We consider that our patient has a type of juvenile PM that can be complicated with spontaneous pneumothorax.

The mechanism of recurrent pneumothoraces in our patient is not clear. The multiple bleb-like lesions played some role in the development of pneumothorax. Other collagen diseases, such as progressive systemic sclerosis and systemic lupus erythematosus, are associated with increased incidence of pneumothorax.[9] Interstitial fibrosis is believed to degenerate alveolar walls, which leads to cyst formation, rapture of the cyst, and spontaneous pneumothorax.[9] A few cases of DM associated with spontaneous pneumothorax have been reported.[1-4,10] Besides interstitial fibrosis, widespread vascular inflammation and infarction are other possible mechanisms of pneumothorax associated with DM.[1] We found no interstitial fibrosis or vascular inflammation in the parenchyma of the lung in our patient.

In general, pleural changes in PM/DM occur primarily in association with interstitial lung disease. In this regard, PM/DM differs from other connective tissue diseases.[8] However, no interstitial changes were found in our patient. This case demonstrates that pleural changes can occur without interstitial fibrosis in a type of PM.

In conclusion, we report a case of recurrent spontaneous pneumothoraces associated with PM. This case presents a different type of pleuropulmonary manifestation of PM.

ACKNOWLEDGMENT: The authors thank Dr. T. Yorifuji of Kyoto University Hospital for providing us with data on the patient.

REFERENCES

[1] Singsen BH, Tedford JC, Platzker AC, et al. Spontaneous pneumothorax: a complication of juvenile dermatomyositis. J Pediatr 1978; 92:771-774

[2] Kobayashi N, Takizawa H, Sugiyama H, et al. A case of dermatomyositis which rapidly developed to respiratory failure in the presence of pneumomediastinum [in Japanese]. Nippon Kyobu Shikkan Gakkai Zasshi 1989; 27:848-854

[3] Romanelli PR, Bastos ME, Zerbini CA. Late diagnosis of juvenile dermatomyositis with spontaneous pneumothorax, pneumomediastinum, and subcutaneous emphysema [in Portugese]. Rev Paul Med 1990; 108:45-48

[4] Jang KA, Kim SH, Choi JH, et al. Subcutaneous emphysema with spontaneous pneumomediastinum and pneumothorax in adult dermatomyositis. J Dermatol 1999; 26:125-127

[5] Collison CH, Sinal SH, Jorizzo JL, et al. Juvenile dermatomyositis and polymyositis: a follow-up study of long-term sequelae. South Med J 1998; 91:17-22

[6] Van Rossum MA, Hiemstra I, Prieur AM, et al. Juvenile dermato/polymyositis: a retrospective analysis of 33 cases with special focus on initial CPK levels. Clin Exp Rheumatol 1994; 12:339-342

[7] Cordone G, Buoncompagni A, Ciccone O, et al. Infantile dermatomyositis: clinical aspects and prospective treatments. Minerva Pediatr 1991; 43:621-630

[8] Serratrice G, Schiano A, Pellissier JF, et al. Anatomoclinical expressions of polymyositis in the child: 23 cases [in French]. Ann Pediatr 1989; 36:237-243

[9] Bates DV, Macklem PT, Christie RV. Pulmonary involvement in the collagen diseases. In: Respiratory function in diseases. Philadelphia, PA: WB Saunders Company, 1971; 299-320

[10] Gayraud M, Lhote F, Valeyre D, et al. Pneumothorax and pneumomediastinum associated with dermatomyositis [in French]. Ann Med Interne 1989; 140:490-491

Masaaki Sato, MD; Toru Bando, MD, PhD; Seiki Hasegawa, MD, PhD, FCCP; Masanori Kitaichi, MD, PhD; and Hiromi Wada, MD, PhD

(*) From the Departments of Thoracic Surgery (Drs. Sato, Bando, Hasegawa, and Wada) and Pathology (Dr. Kitaichi), Kyoto University Hospital, Kyoto University, Kyoto, Japan.

Manuscript received November 11, 1999; revision accepted April 26, 2000.

Correspondence to: Hiromi Wada, MD, PhD, Department of Thoracic Surgery, Kyoto University Hospital, Kyoto University, Shogoin Kawara-cho 53, Sakyuo-ku, Kyoto 6068397, Japan; e-mail: wada@frontier.kyoto-u.ac.jp

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